On how we got to the Doctrine of the Trinity

 Thoughts on Trinity Sunday 2026

Isaiah 40.12–17, 27–end; Psalm 8; 2 Corinthians 13.11–end; Matthew 28.16–20

Last Sunday the focus was squarely on the Holy Spirit because we celebrated the great feast of Pentecost, when the Holy Spirit descended on the Apostles (and Jesus’ Mother with some other women) as tongues of fire in the Upper Room where they had been in constant prayer since our Lord’s Ascension. I hope you are familiar with the story.

And today, as the final act of the Easter Season, and a bridge into what we call Ordinary Time in the Church, we focus on the Holy Trinity: Father, Son and Holy Spirit.

Our Gospel reading today from St Matthew commands us to baptise in the name of the Father and of the Son and of the Holy Spirit, but it’s a sad fact that recent research suggests that most Christians struggle to define or functionally reject trinitarianism. Put simply most Christians don’t understand the Trinity, or have no real place for God as Trinity, in the practice of their faith. It’s been said for this reason that Most Christians are accidental heretics.

But if any doctrine makes Christianity Christian it is the doctrine of the Trinity. The three great ecumenical creeds—the Apostles’ Creed, the Nicene Creed, and the Athanasian Creed—are all structured around our three in one God, underlying the essential importance of Trinitarian theology.

The Athanasian Creed puts it this way: “Now this is the… faith: That we worship one God in trinity and the trinity in unity, neither blending their persons, nor dividing their essence. For the person of the Father is a distinct person, the person of the Son is another, and that of the Holy Spirit, still another. But the divinity of the Father, Son, and Holy Spirit is one, their glory equal, their majesty coeternal.”

It’s a very precise statement of trinitarian belief, and it has a certain elegance to it, but it’s all very technical and abstract isn’t it? So, let’s not leave it there.

I am going to try and clarify the Trinity this morning but I am not going to be using any technical or philosophical terminology. I am going to go back to the Bible, to our story, and explain why I think the doctrine came into being.

Put yourself, if you can, in the shoes of Jesus’ earlier followers. Then keep in your mind the fact that you are a Jew of the 1st century and your cardinal theological belief is that God is ONE. 

Your monotheism is so deep rooted, so foundational to your religious belief and identity as a practicing Jew, that your most important prayer, the Shema, which is recited every morning and evening and goes like this: Hear, O Israel: the Lord is our God, the Lord is One!

And then you spend time with Jesus… You witness miracle after miracle and some of those miracles stray squarely into territory that only ever belongs to God. 

You witness him commanding a storm to be still (Mark 4:35-41) and your mind is drawn back to one of the Psalms of your Tradition that refers to God doing the same thing: He stilled the storm to a whisper; the waves of the sea were hushed (Ps 107:29). You witness him walking on the water (Mark 6:45-52) and you remember that Job 9:8 declares that God alone treads on the waves of the sea.

You watch as he multiplies loaves and fish to feed a multitude (Mark 6:30-44) and you remember that it was God who supplied unlimited bread for your ancestors when they were in the wilderness (Exodus 16). You also watch, dumbfounded as Jesus forgives sins (Mark 2:1-12), which was only ever something God could do; you even hear the Scribes and Pharisees confirm it when they say: Who is this fellow who speaks blasphemy? Who can forgive sins but God alone? (Luke 5:21).

And then there are the healings and the exorcisms and the raising of people from the dead and eventually your rigid, monotheistic mind has to give way to a startling realisation: Jesus is also God.

You still believe in One God, but your monotheism has to give way to a more complex, more nuanced picture.

You know there was a Jewish belief in the Second Temple period (approximately 600 years, from 516 BC to 70 AD) in what was called the Two Powers in Heaven. It proposed that God (Yahweh) has more than one manifestation, with a second, distinct divine figure - often an exalted angel, a visible personification of God, or a pre-existent Son of Man sharing heavenly rule.

So for just one example (there are quite a few) a quick look at Daniel helps.  Daniel 7 portrays a transcendent Ancient of Days alongside a visible, divine Son of Man who is given eternal dominion: In my vision at night I looked, and there before me was one like a Son of Man, coming with the clouds of heaven. He approached the Ancient of Days and was led into his presence.  He was given authority, glory and sovereign power; all nations and peoples of every language worshiped him. His dominion is an everlasting dominion that will not pass away, and his kingdom is one that will never be destroyed (see Daniel 7:13-14).

Ok. Enough of that. We are going to skip forward now to the day of Pentecost. 

Let’s assume that the disciples have allowed their minds to incorporate the possibility that Jesus is God, and this means that the One God they have believed in until now is more complex than they previously thought. 

And then the Holy Spirit comes as tongues of fire and fills them with power and courage and clarity, and a supernatural ability to speak different languages, and you realise that this is also God! There aren’t actually Two Powers in Heaven, there are three; because in some mysterious way that you can’t explain and makes no sense, the Holy Spirit is also God.

And so we arrive at the Christian belief in the Trinity. It goes something like this: God is the Father and God is also the Son and the Holy Spirit. All three are in some inexplicable way, God (this is what we call their essence – or their deepest identity)

But they are also distinct persons because it wouldn’t be right to say that Jesus is the Father or that the Holy Spirit is Jesus or that the Father is the Holy Spirit (see the diagram at the top for clarity).

So Christians didn’t arrive at the doctrine of the Trinity by philosophical reasoning, the Trinity was a conclusion they came to from experience. It was something we came to believe by revelation and all subsequent attempts to put it into words using philosophical language have one purpose – to protect the belief that our God is somehow ONE and THREE. 

And now for a little suggestion – a little trick if you like to keep you trinitarian. The Sign of the Cross.

Now I know that some Anglicans are suspicious of it because it smacks too much of ‘popery’ but I am going to suggest that this amounts to throwing the baby out with the bathwater.

For 1500 years every English Christian crossed themselves as a way of remembering and acknowledging the salvation won for them by the Cross of our Lord, and every English Christian invoked and called on the name of God the Trinity: Father, Son and Holy Spirit. 

So today, on this the feast of the Holy Trinity let’s finish by praying together using the grace at the end of our 2nd reading from the Epistle of St Paul to the Corinthians. 

Cross yourselves as you pray if you feel like it. I always think that praying with the body as well as with words is a fuller expression of faith: The grace of our Lord Jesus Christ, the love of God and the fellowship of the Holy Spirit be with us all, evermore, amen.